Electronic systems and apparatus commonly include various electronic components that are mounted on one or more circuit boards. Many of these electronic components (e.g. processors, controllers, video cards, disk drives, etc.) generate heat. Given that the performance and/or reliability of the electronic components can deteriorate as their temperatures increase, some electronic components include apparatus (e.g. finned heat sinks) that remove heat from the component. To further cool the electronic components, many electronic systems also include cooling apparatus that forces air through the housing where the components reside to remove heat. Such cooling apparatus typically consists of one or more fans or other blowers that direct a flow of air over the circuit board and electronic components to cool the components by convection.
Although the present inventions are not limited thereto, blade servers are one example of electronic apparatus in which it can be difficult to sufficiently cool electronic components. Blade servers are comprehensive computing systems that include processors, memory, network connections, and associated electronics all on a single or multiple circuit boards. For example, one or more server blades may be contained in a enclosure, along with server appliance blades, network-switch blades, storage blades, management blades, local-area-network (LAN) blades, and other blades. The rearward end of the blades frequently include connectors that mate with corresponding connectors on the chassis within the enclosure when the blades are inserted into the enclosure. With respect to cooling, many blade server enclosures include fans or other blowers which create airflow through the individual blade housings. The air flows, from the forward end of the blades to rearward end and over the electronic components, in a direction that is generally parallel to the circuit boards within the blade housings.
The present inventors have determined that conventional cooling apparatus are susceptible to improvement. For example, high heat density from the electronic components require high mass flow and high cooling fluid velocity in order to minimize the film resistance and caloric resistance and, accordingly, reduce the overall resistance to heat transfer from the electronic components to the cooling fluid. The present inventors have determined that conventional cooling apparatus can lead to excessive air turbulence when high mass flow and high cooling fluid velocity are required. Excessive air turbulence can, in turn, result in circuit board vibrations which can cause electronic component and connector failures, poor cooling efficiency and increased power consumption, and index changes that adversely effect free space optics. Turbulence issues notwithstanding, the present inventors have also determined that the manner in which air is directed through conventional electronic apparatus is susceptible to improvement.